Method and apparatus for clarifying liquids

ABSTRACT

Liquids containing contaminating particles of various sizes are treated in a multi-stage system wherein the liquid is delivered into the rear end of a first stage of a tank divided longitudinally into two stages; passing the liquid into contact with and under a pair of baffles; forcing the liquid forward in the first stage to effect a settling of the coarser particles; slowly conveying the settled particles forward, up and out of the first stage of the tank; passing the liquid from the first stage to the second stage through a crossover weir which skims off the cleanest liquid; continuously forcing the liquid down to the bottom of the second stage and under a baffle, minimizing the settling distance for the finer particles; slowly conveying the settled particles forward, up and out of the second stage; and skimming the cleanest liquid at an outlet baffle located at the rear of the second stage adjacent the inlet of the first stage.

United States Patent Schmutzler et al.

[ July4,1972

[54] METHOD AND APPARATUS FOR CLARIFYING LIQUIDS Wis.

[73] Assignee: Jadair, Incorporated, Port Washington,

Wis.

[22] Filed: March 26,1970

[21] Appl. No.: 22,929

Prousman ..210/532 Miller et al ..210/526 X Primary Examiner-John AdeeAttorney-Topel and Jabas [57] ABSTRACT Liquids containing contaminatingparticles of various sizes are treated in a multi-stage system whereinthe liquid is delivered into the rear end of a first stage of a tankdivided longitudinally into two stages; passing the liquid into contactwith and under a pair of baffles; forcing the liquid forward in thefirst stage to effect a settling of the coarser particles; slowlyconveying the settled particles forward, up and out of the first stageof the tank; passing the liquid from the first stage to the second stagethrough a crossover weir which skims off the cleanest liquid;continuously forcing the liquid down to the bottom of the second stageand under a baffle, minimizing the settling distance for the finerparticles; slowly conveying the settled particles forward, up and out ofthe second stage; and skimming the cleanest liquid at an outlet bafflelocated at the rear of the second stage adjacent the inlet of the firststage.

13 Claims, 4 Drawing Figures PATENTEDJUL 4 I912 SHEET 10F 2 QQW ATTORNEYPATENTEDJUL -4 m2 SHEET 2 BF 2 mt m W m M n m 4 5 LH mN WW W DJY METHODAND APPARATUS FOR CLARIFYING LIQUIDS This invention relates to anapparatus and method for clarifying liquids. Although the apparatus andmethod can be used in connection with a variety of liquids andparticulate matter contained therein, the invention will be described asembodied in an apparatus and method clarifying water containing dusts,particles, aggregates and the like, as for example, those found inconcrete and concrete washings, washings from sand and gravels and thoseproduced by asphalt plants.

The enactment of strict pollution control laws requires advancements intechnology to provide positive clarification action at an economicalcost. Many firms which previously emptied polluted streams of liquidsinto rivers, lakes or settling ponds have been served with pollutionabatement orders. Thus, suitable means must be employed for clarifyingthe contaminated liquids to enable the discharge stream to passpollution control requirements. This means apparatus which caneffectively clarify large volumes of water and/or other liquids inrelatively short periods of time. In addition, where water userestrictions limit the amount of water available, reuse of essentiallyall of the water is of prime necessity.

Heretofore, clarifying equipment of various types have been employed.Typical examples are shown in U.S. Pat. Nos. 1,957,168; 2,990,064;3,409,275 and 3,456,798. None of the prior devices employ the novelcombination of structure and steps employed in the present invention.The apparatus and method disclosed herein provides for the treatment ofa variety of contaminated streams both through fixed and portableinstallations with a minimum amount of manpower for installation andoperation. I

A two-stage system utilizing paddles mounted on endless conveyor removesagglomerated solids. Contaminated water is introduced into the receiversection of a first stage where the turbulent influent is quelled andbecomes a fluid dynamically controlled mass flowing smoothly into thefirst stage. Here the initial settling takes place. A crossover weir atthe front of the first stage skirns the cleanest water which is close tothe surface and feeds it to the receiving section of the second stage.The second stage provides final clarification. At the rear of the secondstage, the cleanest water appears near the surface and is withdrawnthrough the clarified water outlet port.

The general object of the present invention is to provide an apparatusfor continuously removing dusts, particles, aggregates and the like fromliquids in a rapid, efficient manner to provide liquids clarified tomeet projected pollution control requirements.

Another object of the present invention is to continuously clarifyliquids to recycle the liquids for reuse with a minimum amount of makeupliquid.

Another object of the present invention is to provide an apparatus forrapid, convenient and economical recovery of contaminating matter orreusable solids from liquids.

Another object of the present invention is to provide a twostagetreatment for differential removal of contaminants.

Another object of the present invention is to provide'a variable speedoperation which can be automatically modified according to the degree ofcontamination and treatment desired.

Another object of the present invention is to provide a specific baffleconfiguration for increased efiectiveness in turbulence suppression andflow control which enhances solids and liquid separation.

Another object of the present invention is to provide conveying meansand paddle configurations for positive movement of solids withoutinhibiting the required settling action.

Yet another object of the invention is to provide apparatus which can beused with a variety of types of pollution control equipment.

The above objects are accomplished by passing contaminated liquids intoa two-stage chamber or tank in which heavier solids are removed in afirst stage and suspended solids are settled out over a period of timeand removed from the second stage. The removal is accomplished by movingpaddles through the liquid and transporting the solids up a dischargeramp and over the edge. Baffles strategically located in both stagesmaterially afiect the action of the apparatus. A variable speed driveand automatic controls regulate residence time to correspond with degreeof contamination and clarification required.

' Ftu'ther details, advantages and objects of the invention will beapparent from the following specifications and appended drawingswherein:

FIG. 1 is a top view of the clarifying apparatus embodying one form ofthe invention,

FIG. 2 is a side view of the clarifying apparatus,

FIG. 3 is a perspective view of a paddle,

FIG. 4 is a schematic perspective, flow diagram of the clarifyingapparatus.

Referring first to FIG. 1, there is shown a clarifying ap paratussuitable for treating a variety of contaminated liquids. The apparatuscomprises a generally rectangular elongated chamber or tank 10consisting of sides 11, rear end 12, disposal ramp 13 and bottom 14. Adividing plate 15 separates a first Stage A from second Stage B. Thedividing plate 15 may be positioned at any point between the sides 1 l,but generally is located at the midpoint and parallel thereto. A weir 16located in the upper forward portion of the dividing plate provides forthe passage of liquid from one stage of the tank to the other. Adrainboard 17 is an integral part of the disposal ramp 13 and leads to adischarge station located below the upper edge of the ramp 13.

Endless chains 18 and 19 are mounted in Stages A and B on sprockets 20and 21 carried on shafts 22 and 23 as shown in FIGS. 1 and 2. Idlers 24in Stages A and B hold down the endless chains 18 and 19 for positionedmovement.

A series of paddles 25 are affixed to the endless chains 18 and 19respectively. The paddles are carried by the rotating endless chains sothat they move forward while in position on the bottom of the tank.Stage A which removes the heavier solids employs paddles spaced at closeintervals. Paddles used in Stage B are of the same design but spaced atlonger intervals. FIG. 3 shows a typical paddle. The paddle consists oflateral upper edges 26 connected to center edge 27 and side flanges 28.Center flange 29 attached to side flanges 28 and center edge 27 hasdrain holes 30 located therein. A continuous hard rubber strip 31 isfastened to flanges 28 and 29 by bolts 33 and a metal backing strip.Ends 32 of strip 31 are tapered toward the edges of flanges 28. A seriesof bolts or rivets connect the paddles to a link 34 forming part of theendless chains 18 or 19.

A series of baffles are positioned at several positions to direct theflow in the tank. Inlet bafile 35 is positioned adjacent to and parallelwith the end 12 of the tank 10. A rear baffle 36 is positioned parallelto inlet baffle 35. The distance between the two baffles 35 and 36 isapproximately twice the distance from bafile 35 to end 12 but isdependent upon the influent flow rate, velocity and composition. Thelower edge of bafile 35 extends below the lower edge of baffle 36.

Inclined bafile 37 is located in the forward portion of Stage Bimmediately behind the rear edge of weir 16. This bafi'le extends downto close proximity with the bottom 14. A discharge baffle 38 ispositioned at the rear of Stage B. The upper edge extends to a pointslightly below the top edges of sides 11. In operation, the water levelis just above the upper edge of the discharge baffle.

A drive chain 40 connects drive means 39 with take-ofi' gear 41 at theforward portion of the tank. Connecting chain 42 provides communicationbetween drive gear 41 and take-off gear 43 mounted on shaft 22. Anautomatic variable control mounted on the drive means 39 is actuated bya sensing device mounted at the outlet. The speed of the endless chains18 and 19 is varied according to the degree of clarity of the discharge.Programmed automatic controls such as a conventional stepping drumprogrammer and delay-off timers, designated schematically at SD? in FIG.2, vary the periods of the conveyors various operating velocities andprovide for periods of non-movement of the paddle and chain system.

The contaminated liquid enters through inlet 44 either by means ofgravity flow or by forced flow. As shown in H6. 1, the inlet ispositioned midway between the side 11 and dividing plate 15. Actual flowis determined by the liquid requirements, residence time required andcomposition of the contaminated liquid. Clarified liquid is taken offeither by gravity flow or pumps.

Referring now to FIG. 4 there is shown a schematic, perspective flowdiagram. The contaminated liquid enters through inlet 44 as indicated bythe arrow in a turbulent state. This turbulent condition is present inthe area between end 12 and inlet baffle 35. Very little settling takesplace because of the unsettled state.

The incoming liquid passes under the lower edge of inlet baflle 35 intothe area between baffle 35 and rear bafile 36. A portion of the liquidwhich is still turbulent has higher energy or curl and moves upwarduntil it strikes rear bafi'le 36 or mixes with other randomly turbulentliquid. This produces a calming efi'ect due to mutual cancellation bythe various turbulent components so that the liquid passing under therear bafile 36 is quelled and becomes a fluid dynamically controlledmass with a minimum amount of disturbing currents. As the liquid movesforward under the lower edge of rear baffle 36, the separation commenceswith the larger particles rapidly settling to the bottom due to thesmall initial settling distance. A natural density stratification beginsto develop with the least dense, cleaner liquid rising upward andincreasingly contaminated, more dense liquid appearing with increasingdistance from the liquid surface. Paddles 25 attached to endless chain18 move the settled matter along the bottom toward the disposal ramp.Paddle and liquid velocities are less than the sediment transport speedfor the particles beingsettled. Sediment transport speed is defined asthe speed or velocity of a flowing stream which will move particles of acertain size, mass and density along the bottom or bed of the stream.

The cleanest liquid in the forward portion of Stage A is skimmed off bythe weir l6 and passes into the next stage. In the liquid remaining, thedegree of contamination increases 40 from top to bottom. Differentialseparation occurs in the area adjacent the moving paddles. The paddlesare moved forward at a speed which allows maximum removal withoutproducing turbulence which would cause the particles to rise into thecontaminated liquid.

The hard rubber edge of the paddles provides a close sweeping actionwithout the abrasiveness of metal'on metal. As a paddle moves forward,it crosses the intersection of the disposal ramp 13 with the bottom 14.There is a tendency for the ends of the lower edge of the rubber stripto drag at the intersection causing the middle of the paddle to risereleasing a portion of the particles. Tapering the end edges of therubber strip as shown in FIG. 3 minimizes the lifting action enabling apaddle to retain the contents in front of it until discharge.

As the paddle moves up the discharge ramp, a limited number of particlesare washed through drain holes 30. Near the upper edge of the dischargeramp the paddle emerges from the liquid and moves up to the lip of theramp where the load is pushed over the edge to the discharge stationbelow. During the interval from the time the paddle emerges from theliquid until discharge over the edge, excess liquid is released throughdrain holes 30. This minimizes the amount of liquid loss and hencemakeup required as well as producing a more solid discharge. The passageof particles through the drain holes 30 at this stage is minimized dueto the increased density of the sediment caused by the compactingagainst paddles.

While the larger particles have been removed in Stage A, the generallysmaller particles remain to be separated in Stage B. As the cleanerliquid containing smaller suspended particles passes through the weirinto Stage B, it is forced downward by inclined baffle 37. Lightturbulence which is created in the liquid during passage through thecrossover weir l6 dissipates during its residence in the chamber createdby the baffle 37, the side 1 l, disposal ramp l3 and the dividingtroduced into the rear portion of Stage B through the opening betweenthe lower edge of the inclined baffle and the bottom.

Therefore, the particulate matter has a much smaller initial settlingdistance.

r The final clarification process for the liquid in Stage 8 isessentially identical to that which took place in Stage A. The

conveyor velocity in Stage B can be set independent from conveyor 18through the use of a split drive. The cleanest water appears near'thesurface at the rear of the unit. The baflle 38 causes this surface waterto be skimmed ofi for discharge through outlet port 45.

The apparatus can be constructed for permanent positioning orportablemounting in order to be versatile for use in various applications. Theapparatus is particularly suited for use in clarifying contaminatedliquid discharged from portable or permanent air washers or airscrubbers, sewage treatment, food processing waste liquids andindustrial waste liquids. The clarified liquid may then be recycled intotal or in part. In other applications, the liquid may be used indifferent processes or discharged for disposal. The solids which areremoved may be a useful by-product or disposed of. The above items areintended to be illustrations of some of the applications of theapparatus. In addition, the apparatus and method described herein aresuitable for clarifying a variety of contaminated liquids.

It is obvious that the general size and dimensions of the apparatus canbe varied as well as materials and standard components. Now that theconstruction and operation of the apparatus as a whole, and itscomponent parts, have been fully explained, it will be understood thatmodifications can be made the scope of the appended claims, and it is tobe further understood that certain features and sub-combinations will beuseful in other systems though particularly well suited to the apparatusdisclosed herein.

We claim:

1. A method of clarifying liquids having solid contaminants dispersedtherein, which comprises:

a. delivering the contaminated liquid adjacent the rear end of a tankdivided longitudinally into two stages into a confined area;

b. continuously passing liquid under a first baffle which reduces theturbulence and a second bafile to reduce the curl, produce a calmingeffect and provide a fluid dynamically controlled mass wherein thelarger particles settle out; continuously forcing said liquid forward inStage A to effect a settling of the coarser materials;

. slowly conveying the coarse settled particles forward in Stage A, upan inclined ramp and over the upper edge of the ramp;

. pasing said liquid through a crossover weir into the forward portionof Stage B;

f. continuously forcing the liquid entering Stage B to the bottom tominimize the settling distance for the finer particles remainingsuspended in said liquid;

. slowly conveying the fine settled particles forward in Stage B, up aninclined ramp and over the upper edge of the ramp;

p$sing the liquid in Stage B to the rear and upward over a dischargebaffle to skim off the clearest liquid;

i. conveying the particles in Stage A and Stage B up the inclined rampfor a brief period of time after emergence from the liquid to allowentrained liquid to drain off prior to discharge over the upper edge ofthe ramp;

3'. collecting the overflow from the discharge baffle and dischargingeither for recycle or disposal;

k. controlling the level of said liquid to prevent overflow.

2. The method of claim 1 wherein the operation is performed according toa predetemrined schedule to assure the removal of required amounts ofcontaminants.

3. The method of claim 1 wherein the movement of the conveying means isautomatically controlled in each stage accorplate 15. The partiallycontaminated liquid is smoothly indin toapredeten'nined program,

4. A system for clarifying liquids having contaminants dispersed thereincomprising:

a. a generally rectangular tank having a bottom, a pair of opposedsides, a rear end, and a disposal ramp all integrally connected, saiddisposal ramp being inclined at an angle so that the upper edge thereofextends beyond the forward edge of the bottom;

b. a dividing plate substantially parallel to and positioned between thesides secured to the rear end, bottom and disposal ramp dividing saidtank into Stage A and Stage B;

c. a crossover weir positioned adjacent the upper edge of the dividingplate and in close proximity to the disposal ramp;

d. conveying means in Stage A adapted for moving coarse solidcontaminants forward, up and over the edge of the disposal ramp;

e. paddles attached to said conveying means;

f. a pair of bafiles positioned adjacent the rear end in Stage g. abaffle adjacent to the rear edge of the crossover weir and inclined inessentially the same manner as the discharge ramp;

h. conveying means in Stage B for moving fine, solid contaminantsforward, up and over the edge of the disposal p;

i. a discharge baffle integrally connected to the side, rear end anddividing plate in Stage B and inclined in essentially the same manner asthe discharge ramp.

j. a drive means for moving the conveying means in Stage A and Bindependently of each other;

k. an inlet positioned adjacent the rear end and substantially midwaybetween dividing plate and the side and between the rear end and theinlet baffle;

I. an outlet positioned above the discharge bafile.

5. The apparatus of claim 4 wherein said paddles are bow shaped with theends extending forward of the middle and having drain holes therein.

6. The apparatus of claim 5 wherein there is a strip of hard,

flexible material attached to and extending below the lower edge of saidpaddles with said strip being tapered upwardly toward the ends of saidpaddle.

7. The apparatus of claim 4 wherein the upper edge of the disposal rampextends above the sides and rear end of the tank.

8. The apparatus of claim 4 further including automatic controls forregulating the conveying means in Stages A and B.

9. A system for clarifying liquids having contaminants dispersed thereincomprising:

a. a generally rectangular tank having a bottom, a pair of opposedsides, a rear end, and a disposal ramp all integrally connected, saiddisposal ramp being inclined at an angle so that the upper edge thereofextends beyond the forward edge of the bottom;

b. a dividing plate substantially parallel to and positioned between thesides secured to the rear end, bottom and disposal ramp dividing saidtank into Stage A and Stage B;

c. a crossover weir positioned adjacent the upper edge of the dividingplate and in close proximity to the disposal ramp;

d. conveying means in Stage A adapted for moving coarse solidcontaminants forward, up and over the edge of the disposal ramp;

e. paddles attached to said conveying means; 7

f. a baffle adjacent to the rear edge of the crossover weir and inclinedin essentially the same manner as the discharge ramp in Stage B;

g. conveying means in Stage B for moving fine, solid contaminantsforward, up and over the edge of the disposal ramp;

h. a discharge baffle integrally connected to the sides and dividingplate in Stage B and adjacent the rear end;

i. a drive means for moving the conveying means in Stage A and Stage Bindependently of each other, and j. an outlet in the rear end of StageB, positioned above the discharge baffle.

10. The apparatus of claim 9 wherein said paddles are how shaped withthe ends extending forward of the middle and having drain holes therein.

11. The apparatus of claim 10 wherein there is a strip of hard, flexiblematerial attached to and extending below the lower edge of said paddleswith said strip being tapered upwardly toward the ends of said paddle.

12. The apparatus of claim 9 including automatic controls formaintaining constant level and regulating movement of the conveyingmeans in Stage A and Stage B.

13. The apparatus of claim 9 wherein the upper edge of the disposal rampextends above the sides and rear end of the tank.

2. The method of claim 1 wherein the operation is performed according toa predetermined schedule to assure the removal of required amounts ofcontaminants.
 3. The method of claim 1 wherein the movement of theconveying means is automatically controlled in each stage accordin to apredetermined program.
 4. A system for clarifying liquids havingcontaminants dispersed therein comprising: a. a generally rectangulartank having a bottom, a pair of opposed sides, a rear end, and adisposal ramp all integrally connected, said disposal ramp beinginclined at an angle so that the upper edge thereof extends beyond theforward edge of the bottom; b. a dividing plate substantially parallelto and positioned between the sides secured to the rear end, bottom anddisposal ramp dividing said tank into Stage A and Stage B; c. acrossover weir positioned adjacent the upper edge of the dividing plateand in close proximity to the disposal ramp; d. conveying means in StageA adapted for moving coarse solid contaminants forward, up and over theedge of the disposal ramp; e. paddles attached to said conveying means;f. a pair of baffles positioned adjacent the rear end in Stage A; g. abaffle adjacent to the rear edge of the crossover weir and inclined inessentially the same manner as the discharge ramp; h. conveying means inStage B for moving fine, solid contaminants forward, up and over theedge of the disposal ramp; i. a discharge baffle integrally connected tothe side, rear end and dividing plate in Stage B and inclined inessentially the same manner as the discharge ramp. j. a drive means formoving the conveying means in Stage A and B independently of each other;k. an inlet positioned adjacent the rear end and substantially midwaybetween dividing plate and the side and between the rear end and theinlet baffle; l. an outlet positioned above the discharge baffle.
 5. Theapparatus of claim 4 wherein said paddles are bow shaped with the endsextending forward of the middle and having drain holes Therein.
 6. Theapparatus of claim 5 wherein there is a strip of hard, flexible materialattached to and extending below the lower edge of said paddles with saidstrip being tapered upwardly toward the ends of said paddle.
 7. Theapparatus of claim 4 wherein the upper edge of the disposal ramp extendsabove the sides and rear end of the tank.
 8. The apparatus of claim 4further including automatic controls for regulating the conveying meansin Stages A and B.
 9. A system for clarifying liquids havingcontaminants dispersed therein comprising: a. a generally rectangulartank having a bottom, a pair of opposed sides, a rear end, and adisposal ramp all integrally connected, said disposal ramp beinginclined at an angle so that the upper edge thereof extends beyond theforward edge of the bottom; b. a dividing plate substantially parallelto and positioned between the sides secured to the rear end, bottom anddisposal ramp dividing said tank into Stage A and Stage B; c. acrossover weir positioned adjacent the upper edge of the dividing plateand in close proximity to the disposal ramp; d. conveying means in StageA adapted for moving coarse solid contaminants forward, up and over theedge of the disposal ramp; e. paddles attached to said conveying means;f. a baffle adjacent to the rear edge of the crossover weir and inclinedin essentially the same manner as the discharge ramp in Stage B; g.conveying means in Stage B for moving fine, solid contaminants forward,up and over the edge of the disposal ramp; h. a discharge baffleintegrally connected to the sides and dividing plate in Stage B andadjacent the rear end; i. a drive means for moving the conveying meansin Stage A and Stage B independently of each other, and j. an outlet inthe rear end of Stage B, positioned above the discharge baffle.
 10. Theapparatus of claim 9 wherein said paddles are bow shaped with the endsextending forward of the middle and having drain holes therein.
 11. Theapparatus of claim 10 wherein there is a strip of hard, flexiblematerial attached to and extending below the lower edge of said paddleswith said strip being tapered upwardly toward the ends of said paddle.12. The apparatus of claim 9 including automatic controls formaintaining constant level and regulating movement of the conveyingmeans in Stage A and Stage B.
 13. The apparatus of claim 9 wherein theupper edge of the disposal ramp extends above the sides and rear end ofthe tank.